Biology 2 Chapter 9

Biology 2 Chapter 9 - Chapter 29: Respiration • In the...

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Unformatted text preview: Chapter 29: Respiration • In the US, about 3,000 teenagers take up smoking every day • Just one cigarette immobilizes cilia that line airways of the lungs for hours, preventing them from sweeping away airborne pathogens and pollutants • Nicotine has many side effects, including constriction of blood vessels and raising BP • Smoking ↑ the risk of deadly lung cancers • Secondhand smoke causes about 3,000 lung cancer deaths each year Impacts & Issues Why Exchange Gases? • Gas exchange supports cellular respiration • In vertebrates – O 2-rich air inhaled and O 2 deposited in blood – O 2 transported to body cells by blood – Blood transports CO 2 from tissues to lungs – CO 2 released from lungs (and body) during exhalation Common Features of Animal Respiratory Systems • All animal respiratory systems share 3 features – (1) Respiratory surface must be moist so gases can diffuse across cell membranes – (2) Cells lining respiratory surface are thin to optimizes gas diffusion – (3) The respiratory surface area must be large to allow for adequate gas exchange Some Animals in Moist Environments Lack Specialized Respiratory Structures • Gases diffuse short distances in smaller animals to reach cells – Gas exchange optimized by long, flat bodies with greater surface area – Examples: roundworms and flatworms Some Animals in Moist Environments Lack Specialized Respiratory Structures • Low energy demands translate into larger animals that rely on their moist body surface for gas exchange – Larger size possible because less O 2 needed by cells – Example: Jellyfish Some Animals in Moist Environments Lack Specialized Respiratory Structures • Some animals bring the environment close to all their cells – Allows greater exposure of cells to O 2 – Example: Sponges Some Animals in Moist Environments Lack Specialized Respiratory Structures • Other animals combine large skin surface area with well-developed circulation for delivery to cells – Skin has many capillaries that carry O 2 to internal body tissues – This arrangement sustains a favorable O 2 concentration gradient between skin and blood – Example: Earthworm Respiratory Systems Facilitate Gas Exchange • Respiratory systems more effectively exchange gases between the environment and an animal’s body • Respiratory systems alternate bulk flow of air/water and diffusion of gases • Bulk Flow: describes when fluids or gases move through spaces from high pressure to low pressure Respiratory Systems Facilitate Gas Exchange • In mammals – Air moves past respiratory surface by bulk flow (down pressure gradient) – O 2 and CO 2 are exchanged by diffusion – Gases transported to/from tissues by bulk flow – Gases exchanged with tissues (cells) by diffusion Oxygenated blood Deoxygenated blood CO 2 O 2 CO 2 O 2 CO 2 CO 2 CO 2 CO 2 CO 2 alveoli (air sacs) left atrium right atrium right ventricle left ventricle O 2 Gills Facilitate Gas Exchange in Aquatic Environments...
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This note was uploaded on 10/10/2011 for the course BIOL 1002 taught by Professor Pomarico during the Fall '08 term at LSU.

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Biology 2 Chapter 9 - Chapter 29: Respiration • In the...

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